The ranges seem to be dependent on the scale of the object: suppose your highpoly object has Scale=1 and sticks out of lowpoly for 0.01m, the Cage extrusion required for clean bake will be 0.01m (at least). And if you scale the object without applying it will still be 0.01m.
Same for Mar Ray Distance but in the opposite direction. I think.
In advance, sorry if this post is unasked for 